On a plaza in downtown Las Vegas, a set of new streetlights is completely disconnected from the grid: the poles create power both from sunlight and through special tiles that harvest the kinetic energy of pedestrians walking by.
"We're interested in testing both technologies," says Jorge Cervantes, the city's executive director of community services. "We've tested solar streetlights before and they've been successful. The kinetic we hadn't tested. The kinetic really intrigued us in that 40 million people come visit Las Vegas every year, and 20 million of those come downtown… we get a lot of foot traffic in that area where we want to try this out."
The smart lights, made by a New York City-based startup called Engoplanet, run LED lights, and also provide WiFi, cell phone charging stations, and a system of sensors that can help the city remotely track things like air quality.
Though the company also makes a solar-only version of the light, in some locations, harvesting footsteps also makes sense.
"We also wanted to offer a unit that would combine solar and kinetic energy, to be suitable for installation in many areas that have limited access to the sun," says CEO Petar Mirovic. "Let’s take Manhattan for an example. Many parts of the city have very limited exposure to the sun due to tall towers and buildings. However, there is so much foot traffic and [there are so many] pedestrians that can create a lot of power through kinetic energy creation."
In most areas, most of the power would come from the sun; a single footstep can generate only four to eight watts of power, and the streetlight needs 800 to 900 watts of power each day. But in the four-block long stretch of downtown Vegas where most tourists come, a video canopy blocks sunlight from the area. The foot traffic, on the other hand, is heavy. (An upcoming version of the light will also be able to generate power inside roads, harvesting energy from passing cars; that can generate about 10 watts a car).
The pilot test in Las Vegas is also closely looking at battery performance, because past lights have struggled with the city's heat. "One of the challenges we've had in Las Vegas before when we've tested solar streetlights is the battery life," says Cervantes. "Our summers get up to about 120 degrees."
The new lights have only been in place for a couple of months, and the city will keep monitoring performance before moving forward with more installations. "We really want to go through one of our hot summers to gauge how useful they are," he says.
Las Vegas's city facilities, from streetlights to government buildings, now all run on 100% renewable energy. Much of it comes from a massive nearby solar farm. But the city also relies on smaller on-site generation.
"When we went to 100% renewable, we're paying a slight premium on what the regular rate would be, because we thought from a sustainability standpoint it was worth it," Cervantes says. "But to the extent that we can generate power, then it lowers our overall cost portfolio."
The city now generates roughly five megawatts of power through its own facilities—and the new streetlights are a tiny part of that number.